The object of the present invention is to provide a timepiece including a time standard, a divider circuit, at least one electric motor, a pulse forming circuit to provide for forward or reverse rotation of said motor a gear train, a display arrangement including an hours hand and a minutes hand and a dial divided into 60 divisions.
Timepieces of the above mentioned type are known. In U.S. Pat. No. 4,182,114 is described a timepiece movement including an electric motor and a planetary dial train having special advantages when utilized in wrist-watches of extremely small dimensions. In this arrangement there is no seconds hand nor has a date display been provided in order to enable a considerable reduction of the overall dimensions of the timepiece. Moreover since the minutes hand is driven directly by the stepping motor, such motor may be energized less often than when a seconds hand is provided thereby effecting a reduction in the energy consumption so that one may employ smaller batteries. These several advantages combine furthermore with elimination of the supporting base plate, thanks to the suppression of the numerous mechanical pieces normally required for correction of timepiece movements of the prior art and enable one to achieve a special styling which may find application in a ladies wrist-watch or for fine jewellery.
The absence of seconds hand in such a movement may be considered as a negative type modification but since hereby one may achieve a significant reduction in the dimensions of the watch it may nevertheless be considered as an improvement. However circumstances arise where a seconds hand can be useful even should this be only during a limited time. For instance a medical assistant may wish to measure the pulse of a patient and everyone may occasionally wish to carry out time measuring operations.
The idea of the present invention thus consists in being able to use at least one of the two hands in order to momentarily display the second, thus adding to the watch on additional performance without increasing its dimensions nor increasing its energy consumption significantly. In the particular case one may realise a chronographic function in the full sense of the term this being achieved by means of a single manual control which may be present in the form of a push button.
The French patent application No. 2 404 250 has already proposed a timepiece having a minutes hand and an hours hand adapted such that they may display various functions in addition to those for which they are initially intended. By means of a push button P.sub.1 it is possible to display through use of the minutes hand, successively, the date, the month, the hour and the second. At the same time the internal circuit of the timepiece is arranged in order to correct the different mentioned functions, the correction being obtained through use of another push button P.sub.2. This patent application has thus as an essential purpose the correction of the time indications and neither proposes nor suggests, as in the present case, a true chronograph function where through a first action on a push button the hands are set at noon, in a second operation the minutes hand becomes a seconds hand, and in a third action the hands are stopped in order to permit reading of the elapsed time. Finally in a fourth action the hands are restored to their original function in order to indicate hours and minutes in real time. Moreover as has already been said, the watch of the present invention has a very simple movement devoid of all internal contacts which need be operated by a cams coupled with the hands as has been the case in the cited patent application. Finally the time setting of the watch of the present invention is achieved through means independent of those used for obtained the chronograph function, such correction means being those described for instance in the U.S. Pat. No. 4,185,453 assigned to the present assignee. In this patent correction of seconds is achieved without the necessity of a seconds hand for display thereof as is the case in respect of French application No. 2 404 250 mentioned above which employs a hand normally indicating minutes to display seconds in order to enable correction of the seconds display.
It is the purpose of this invention to bring initially the hours and minutes hand of a timepiece not having a seconds hand to noon before having them assume the function of minutes and seconds hands respectively in order to be able to perform a chronograph function.
These purposes are obtained thanks to the claimed means.